1. Field of the Invention
This invention relates to improvements in ring laser gyroscope accuracy, and more particularly to the electronic circuitry used to process the electronic signals emanating from the ring laser gyro optical detector typically employed for use with a ring laser gyro, This invention even more particularly relates to a circuit for increasing the resolution of a ring laser gyroscope,
2. Description of the Prior Art
Ring laser gyroscopes are known in the art to produce outputs comprised of optical fringes occurring at a rate dependent upon the rate of rotation of the ring laser gyroscope in inertial space, Typically, two outputs are developed from a ring laser gyro optical detector coupled to the ring laser gyro, The ring laser gyro optical detector typically contains an excited photo diode array which when illuminated detect the optical frequency difference of clockwise and counterclockwise laser beams within the ring laser gyroscope, The photo diode array generates a two phase resolver type signal wherein one signal leads the other or lags the other by 90 degrees, depending upon the sense or direction of rotation of the ring laser gyro body in inertial space of the ring laser gyroscope.
One circuit that has been advanced includes a pulse modification circuit for each output line including a preamplifier and trigger squaring circuit together with logic circuitry to produce a first output representing clockwise pulses and a second output representing counterclockwise pulses. The output pulses produced by this apparatus tracked, one for one, the output pulses of the ring laser gyroscope; consequently, the resolution of the entire circuit was limited by the pulse output frequency developed by the ring laser gyroscope.
Another circuit that has been advanced is described in an application for U.S. Patent, titled Apparatus for Increasing the Resolution of a Laser Gyroscope, Ser. No. 457,845, filed Jan. 14, 1983, naming this same inventor and common assignee. The object of this circuit was to provide an output pulse rate at a multiple of the pulse rate developed from the frequency difference of the clockwise and counterclockwise laser beams within the gyroscope. Another object of this invention is to provide a direction signal for use in processing the output pulse signals. The output pulse signals from this invention circuit are adapted to be applied directly to an up/down counter. This circuit is constructed of digital circuit elements and as such is unlike and does not anticipate the invention ring laser scale factor enhancement circuit which depends on linear circuit elements and functions based on analog circuit principles and trigonometric identities.